Method of producing nitric acid.



combinations of steps constituting UNITED STATESPATENTTO IQE i;

wAI-m s. mania, or m you, if. Y.,ZA88IG1IOB,TQIRAIIK s. wemunn:

., remnant.

union or rmnucme mrnrc horn.

1,292,s14.- in Drawing.

Improvements in Methods of Produc" 'Nitrlci Acid; and. I do hereb declm the iiowin' to bee. full, V

cleaner descfigtion'of. e invention, such as willcenable (it v same. This invention relatesto a roducing nitrose suitab e? for me, nitric acid, and I said in a nmnne'r'n ore eflicie'nft (and less cosvtyththan has. been heretofore proposed.

this and other objects .111 view the.

invention. i in the novel 7 1? P ass, all aswill he more-fully heremefter disl'ticulerly o'utin the v In my Patents 8, 1916, entitled Process of, end'apperatli's for Aug. e, 1916; and entitled Hethod'oi oiidiz- 'a, Lhave the essential pnnci lee governing oxide tipn o elnmoniato 600 (1m 7009 j inth jeets lyzer, the combustion; of gmmenia with roportio'ns of for e p fiI hQn of nitric acidedoesg ndt yield T;

I it

have no Yali'1e commensurate I fIfione towrite a. similar equation h m n; m rebrm u, 1am. m n I; uomi.

s in thwart to which'it npper'teins tom-eke end use the" as forjtefobject' tO form L O V -su1ta hle for the production of nitric acid, ,hnd-lttisfound n to use from 1} to y 'dicizted,'- e flametempernturewill be very. I Innch lower. necessary for min I taming combustion; In order, thereforeyki it is |;v'.': :r oxidizing'ammonie, 'andNo'. 1193196, dated y an at started. Many suppiied this manual forms of appiiratus by preheating mixture'of end ammonia through a;-

' engzof upper-ates,-

@It is well known with ,the gt-{the ammonia, seiregty yearsityas also noted that an,

" resenee of a suit-' result, but when one considers 'peratures of the cataly'zers in use are quite Bpeefllceflon of Patented J 28,

representing the combustion in eirgwe ca-n essume'that the a1r-consisls approximately of somgmog so'f that our equation wo Y ew York,- ha've invented ceri 4NO+6T,O+20N, This the, valuable nitric oxi d which cal'lconvertedbywell knownmethod's Into nitrous or nitric acids, or correspo'n salts of the But as amatter of filct catalytic combustion with air, or with oxygen, more than the theoreticel quantity 0 oxygen to insure comflete combustion to those higher oxide 0 nitrogen bll'm dmgos 2% times the theoretical quantity of air, the

exces thmugh unchanged; 7 Naturof air as above ina co'n'tinu'ous combustion of the aml hh" l: ieii p ymg eattojt e reaction emp oy Keiwise thejflmnewill out, even if inventors in field have additional heet' in'their com- P es w i-must. be t sum m up -d fis n x 'Which the reaction to comparatively w tempera tures; an erefore,-'1iny considerable pm of the ammoniaeair mixture will cause Ldecomposition oftheflammonie be-' 5 170.700" 0. 'nry.

. that ammonia gas into nitrogen and hydrogen '::V'...; .-.fl'y.ea :In oxygen-bi courseitbnrns; with ut ion fore it"thecatel zer,andsocausea.

close to the flame tem and, therefore,.can radiate a huge quantity of heat 4 w may not be suflicientto raise the of the ammonia. to.

lowfefliciencyonnationto nitrosegases.

back into the oncoming gas current, we can readily see that the intentional preheating plus the'absorbed radiated heat creates temperatures in the ammonia-air mixture which It is further readily seen that under cer tain conditions this disassociation may take place to only a small extent, thereby setting free hydrogen which has a very low ignition temperature, and that this hydrogen may then be ignited in the air-mixture, creating an excessive local temperature as it burns, and-so further increasing this decomposition of ammonia before strikin the catalyzer. As a matter of fact, it has heenvfound that most commercial types ofapparatus operat ing upon this principle decompose from 5 to 15% of the ammonia by a combination of the above causes before the ammonia-air mixture ever strikes the catalyzer, and there fore, they yield a correspondingly low efiiciency oftransformation of ammonia into nitrose gases. y

In ,the process of my said Patent No. 1193796, I am careful, as above stated, to employ an excess ofair above that theoretically required, in order to attain the desired higher; oxide of nitrogen, ,and owing to this saidv excess of air, the catalyzer must be continuously supplied with heat from an outside source.

In this invention, on the other hand, I avoid the necessity of artificially heating the catalyzers, by enriching the air to be mixed with the ammonia with a uantity of oxygen to make the reaction sel propagating, That is to say, I have found that if instead of using .atmospheric air containing,

say 20% oxygen and.80% nitrogen, one em ploys an excess of an enriched air containi say 30% to 40% oxygen the catalytic oxidiz ing reaction becomes self supporting, even though said excess of air is resent; and the catal. zers need not in sue cases be artificial y' heated except incidentally, or to start the reaction.

I have further found that a convenient method of obtaining this enriched air, is by liquefying atmtlpheric air, and pgnnitting the nitrogen to boil ofi until ut 40% oxygen or a somewhat higher percentage is left. 1 The ammonia used in th s process can be conveniently obtained by'treating calcium cyanamid with steam, and the nitrogen boiled ofi can be conveniently used in, the manufactureof said cyanamid. It thereforefollowsthat the waste gases from a liquid air plant roducing nitrogen can be employed to eliminate the necessity of heat-J gas, such as that disclosed, not only are con-- centrations of the exit gases of at least double these values easily attained but the oxygen enriched air being in excess considerable free oxygen passes the catnlyzers and serves to oxidize the nitrose gases present to those higher oxids of nitrogen so necessary. a

for the commercial production of nitric acid. I therefore produce a greater efliciency than heretofore 1n condensation and concentration yields; and I also obtain by this procedure higher percentages of nitric acid,

lyzer mass the free oxy en that has been provided beyond the cata yzer by the above For I find after the lower oxids of It is obviousthat those skilled in the art' may vary the details of the invention with I p v out departing from the spirit thereof, and therefore, I 0

not wish to be limited to the above disclosure except as may be required by the claims.

What I claim is 1. The process of producing the higher oxids of nitrogen suitable for making nitric acid which consists in providing a mixture of oxygen, air and ammonia containing an excess of air and sufiicient oxygen to sustain the. reaction, and subjecting said mixture to the action of a hot catalyzer, substantially as described,

2. The process of; oxidizing ammonia to form higher oxide of. nitrogen suitable for making nitric acid which consists in providing a mixture of'oxygen, ammonia and air in excess containing above 25% oxygen; passing said mixture through a catalyzer; and ralsing said catalyzer to a temperature suflicient to start the reaction, substantially as described. a

3. The process of oxidizing ammonia to form higher oxids of nitrogen which consists in providing a mixture of ammonia, oxygen and air in excess-said mixture contai 'ng above 25% of oxygen; subjecting sai mixture to a cooling action; subjecting the cooled mixtureto the action of a catalyzer; and raising said catalyzer to a temperature suflicient to start the reaction, substantially as described.

4. The process of producing'higher oxids of nitrogen suitable for making nitric acid which consists in providing a mixture of oxygen, air and ammonia containing an excess of air and sufficient oxygen to sustain the reaction, but an insufiicient quantity of nitrogen to lower the flame temperature below the ignition point, and subjecting said mixture to the action of a hot catalyzer, substantiaily as described.

In testimon whereof I afiix my signature,

in presence 0 two witnesses.

WALTER S. LANDIS.

Witnesses:

H. L.'MARTENET, Joan J. ELBUT. 

